AUGUSTA — Twenty-two light stations in Maine will be open for tours in what’s billed as the largest event of its kind in the country.

The fourth annual Maine Open Lighthouse Day runs through the day on Saturday. Coastal, island and river lighthouses will welcome the public for tours and special activities.

The event is coordinated by the U.S. Coast Guard, in partnership with the Maine Office of Tourism and the American Lighthouse Foundation.

Most sites (www.lighthouseday.com) will be open to visitors from 9 a.m. to 3 p.m. for guided or self-guided tours of keeper’s houses and light towers. Some light stations will have limited accessibility or special restrictions.